# Magnetization reversal, giant exchange bias effect and magnetoresistance in oxygen vacancy ordered Sr$_{4}$Fe$_{3}$CoO$_{11}$

## TL;DR

This study explores the magnetic, transport, and structural properties of Sr₄Fe₃CoO₁₁, revealing complex magnetic reversal, giant exchange bias, and magnetoresistance effects driven by magnetic frustration and anisotropy.

## Contribution

It reports the first detailed investigation of the magnetic reversal, exchange bias, and magnetoresistance in oxygen vacancy ordered Sr₄Fe₃CoO₁₁, highlighting the role of magnetic frustration.

## Key findings

- Magnetic reversal occurs at 47 K with increased anisotropy.
- Negative magnetoresistance reaches 80% at 25 K in 7 T.
- Giant exchange bias observed below T_N due to magnetic frustration.

## Abstract

We report the structural, magnetic, exchange bias and magnetotransport effect in Sr$_{4}$Fe$_{3}$CoO$_{11}$. The material crystallizes in the orthorhombic $\textit{Cmmm}$ space group. It shows antiferromagnetic (G-type) transition (T$_{N}$ = 255 K) along with interesting temperature induced magnetization reversal (T$_{Comp.}$= 47 K measured at 100 Oe). The magnetic reversal can be elucidated considering the increased magnetocrystalline anisotropy with Co substitution. Magnetoresistance measurements shows an interesting crossover from negative to positive side at $\sim$ 100 K. The negative magnetoresistance reaches 80 $\%$ at 25 K in 7 T magnetic field. Giant exchange bias effect is observed below T$_{N}$ under field cooling condition. The origin of the negative magnetoresistance and giant exchange bias in this sample can be attributed to the magnetic frustration.